| 摘要 |
A water-activated alarm system, providing an alarm in the event of a water leak, includes a radio-frequency transmitting unit and a receiving unit and a number of safety features to ensure proper operation in the event of an emergency. The transmitting unit includes a flood detector having electrodes to be placed in a flood prone area, a tone encoder, for sending an encoded signal in the event of a flood, and means to provide visible and audible alarm indications, including a buzzer and a user-programmable digital voice circuit for identification of the area in which a flood occurs. The receiving unit includes a superheterodyne receiver or a super-regenerative receiver and detector, a tone decoder to prevent false alarms, a battery charger, a solenoid valve for shutting off the flow of water in the event to a leak detected by the transmitting unit, and a freeze-guard circuit using a peltier device to keep the solenoid valve within a temperature range allowing valve operation during freezing weather conditions.
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